Although many would say that I'm still young in years, I can say with confidence that my definition of happiness has come to evolve as I have grown and matured:
When I began to truly give interest to matters of the spirit and matters of the heart, I believed that happiness came from being able to find success and find the material things I desire.
As time has progressed, I've been given favor from the universe: I've been given anything and everything I could have wanted, I've met successes that I thought would bring me happiness, but, now that I've become independent and am now living on my own, I see that the only thing I was feeling was a constant pressure to strive and meet expectations.
I'm a student now, and I'm in the place that my journey has brought me. I no longer measure happiness as what I have or what the things I've done can bring me, but I have begun to gauge happiness by my ability to be content in my current state.
Who can say how I will feel in the years to come? Who is to say that what I say carries any weight? Well, the answer to these questions, I guess, is the same as the one to the question posed in the original post: I don't know, but I am not opposed to my circumstances.